Just like Eugenia yesterday, I also upgraded my laptop's Ubuntu Feisty installation to Gutsy a few days ago. The upgrade process went completely awry, though, so I was forced to do a fresh install. Not a bad thing, as it gave me the opportunity to take a look at Ubuntu's soon-to-be-released Gutsy Gibbon with GNOME 2.20

The ease of upgrade of Debian systems is much more down to the packages than apt itself. Apt tends to be better at working out solutions for dependency conflicts than some other high-level package managers, but you'd need an AI to guarantee the correct solution. We do our best to test upgrades using packages provided within the distribution and add hints to the upgrade manager to deal with some awkward corner cases, but if you've installed packages from elsewhere then it can become very difficult to make this all work properly.

Using the update manager is always the recommended way of handling upgrades, though. One thing it ought to ensure is that you've got a functional desktop setup after the update. If that's not happening then it's a bug, and we'd be very interested in finding the details in order to make sure nobody else hits it.